• A. Miyamoto, K. Goto, S. Sasaki
  HSRC, Higashi-Hiroshima
• S. Hanada
  Hiroshima University, Graduate School of Science, Higashi-Hiroshima
• H. Tsutsui
  SHI, Tokyo

The HiSOR is a synchrotron radiation (SR) source of Hiroshima Synchrotron Radiation Center (HSRC), Hiroshima University, established in 1996. HiSOR is a compact racetrack-type storage ring having 21.95 m circumference, and 400-nmrad natural emittance, which is not so small compared with those of other medium~large storage rings. There are 14 beamlines on HiSOR, but the ring has only two straight sections for undulators which are obviously not compatible with modern SR facilities. Therefore, we are planning to construct a compact storage ring, 'HiSOR-II' in which undulators are dominant light sources. We refer to the electron storage ring MAX-III as the best models to design HiSOR-II lattice. This 700 MeV storage ring is designed that the circumference is equal to or less than 50 m so that it can fit in our existing site. It has several straight sections for undulators, and its natural emittance is about 14nmrad. The booster ring aiming for the top-up injection is constructed on the inside basement of HiSOR-II. This layout brings advantages in radiation shielding and prevention of magnetic field interference between two rings.